Use of home energy management systems (HEMSs) for managing energy consumption in houses is becoming widespread. The HEMS includes a device management apparatus wirelessly communicating with devices installed in a house or the like. The device management apparatus executes a management program continuously for almost 24 hours to manage the devices installed in the house. The management program is a program executed by the device management apparatus for controlling the devices, and is generally updated as appropriate for addition, deletion, or change of functions, or for correction of defects.
Techniques are proposed regarding update of programs executed by devices (for example, Patent Literature 1 and 2), and techniques are proposed regarding update of programs executed by power management apparatuses (for example, Patent Literature 3).
For example, the Patent Literature 1 discloses a controller device counting the use/non-use of radio waves in each time slot, sending to a household electric appliance an electronic message to start a process of storing a new update program during a time slot having the lowest time-slot count, and starting transmission of the update program.
For example, the Patent Literature 2 discloses rescheduling of reserved operation times of multiple household electric appliances so as to ensure that the time slot for which none of the multiple household electric appliances are reserved for timer operation is equal to or larger than the minimum time necessary for updating the programs of program-update target household electric appliances.
For example, the Patent Literature 3 discloses one-apparatus-at-a-time isolation of N cooperating power management apparatuses, in order to update software.